Agriculture Reference
In-Depth Information
ous whitish markings;
hindwings
brownish.
Egg
hemispherical, distinctly ribbed and reticu-
lated; mainly whitish, becoming brownish.
Larva
up to 45 mm long;
body
varying from
green to blackish-brown, with blackish markings
along the back (these form a saddle-like mark on
the slightly humped eighth abdominal segment),
and a pale spiracular band;
spiracles
white with
black rims;
head
pale brown.
Young larva
pale
green and shiny, speckled with black; later,
banded with yellow intersegmentally.
Pupa
17-
22 mm long, reddish-brown and finely sculp-
tured;
cremaster
with two short, hooked spines.
Melanchra persicariae
(L.)
Dot moth
The polyphagous larvae of this generally com-
mon moth attack various herbaceous plants, in-
cluding beet, brassicas and potato, and are
sometimes minor pests in allotments, gardens
and nurseries. The larvae feed voraciously and, if
numerous, can cause significant defoliation.
Fig. 323 Dot moth,
Melanchra persicariae
(x3).
BIOLOGY
Moths occur mainly from June to August and
deposit their eggs singly or in untidy batches on
the leaves of various plants. The eggs hatch
about 8 days later. Larvae feed until the autumn
and then pupate in flimsy cocoons formed in the
soil. Adults emerge in the following year.
DESCRIPTION
Adult
38-48 mm wingspan;
forewings
bluish-
black, with a prominent, white reniform stigma;
hindwings
greyish but whitish basally
(Fig.
323). Egg
hemispherical, ribbed and slightly
reticulated, whitish-green becoming pinkish-
brown.
Larva
up to 45 mm long;
body
pale
brown or pale green, with a white line along the
back and darker V-shaped markings that are
particularly obvious on abdominal segments 1, 2
and 8 (these segments also noticeably humped);
head
pale brown;
prothoracic plate
brown or
green, with three white lines
(Fig. 324). Pupa
22-24 mm long, chestnut-brown;
cremaster
with
two short, divergent spines.
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Fig.
324
Larva of a dot moth,
Melanchra persicariae
(x2).
Mesapamea secalis
(L.)
Common rustic moth
This pest is associated mainly with grasses but
will also attack cereals, causing the death of cen-
tral shoots. The larvae are typical ley pests and
